WO2015017850A2 - Partially sulfonated polymers and their use in hydrocarbon recovery - Google Patents

Abstract

Partially sulfonated polymers are disclosed. The partially sulfonated polymers may include a polymer chain with a plurality of monomeric units. The monomeric units may include sulfonated monomeric units associated with sulfonate moieties, and unsulfonated monomeric units that lack the sulfonate moieties. The unsulfonated monomeric units may include between about 5% to about 90% of the monomeric units of the polymer chain. The partially sulfonated polymers may be utilized in recovering hydrocarbons from a geological structure by injecting a composition that includes partially sulfonated polymers into the geological structure and collecting the composition after flow through the geological structure.

Description

TITLE

PARTIALLY SULFONATED POLYMERS AND THEIR USE IN HYDROCARBON

RECOVERY

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to U.S. Provisional Patent Application No. 61/861,834, filed on August 2, 2013. The entirety of the aforementioned application is incorporated herein by reference.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH

[0002] Not applicable.

BACKGROUND

[0003] Polymeric compositions have numerous performance limitations, including limited mobility and stability in underground reservoirs. Furthermore, the fabrication of such polymeric compositions can be costly. Therefore, there is a desire for more affordable and stable polymeric compositions for various applications, including enhanced oil recovery.

SUMMARY

[0004] In some embodiments, the present disclosure pertains to partially sulfonated polymers. In some embodiments, the partially sulfonated polymers include a polymer chain with a plurality of monomeric units. In some embodiments, the monomeric units include sulfonated monomeric units associated with sulfonate moieties, and unsulfonated monomeric units that lack the sulfonate moieties.

[0005] In some embodiments, the polymer chains of the partially sulfonated polymers include sulfonated polystyrene. In some embodiments, the sulfonated monomeric units of the partially sulfonated polymers include sulfonated styrene. In some embodiments, the unsulfonated monomeric units of the partially sulfonated polymers include styrene.

[0006] In some embodiments, the sulfonated monomeric units are derived from the unsulfonated monomeric units of the partially sulfonated polymers. In some embodiments, the unsulfonated monomeric units are derived from the sulfonated monomeric units of the partially sulfonated polymers. In some embodiments, the unsulfonated monomeric units include between about 5% to about 90% of the monomeric units of the polymer chain.

[0007] Some embodiments of the present disclosure pertain to recovering hydrocarbons from a geological structure. In some embodiments, recovering hydrocarbons from a geological structure includes injecting a composition into the geological structure, where the composition includes one or more partially sulfonated polymers of the present disclosure. In some embodiments, the hydrocarbon recovery includes collecting the composition after flow through the geological structure. In some embodiments, the flow results in association of the hydrocarbons in the geological structure with the composition.

[0008] In some embodiments, the hydrocarbon recovery includes separating the hydrocarbons from the composition. In some embodiments, the geological structure is an oil and/or gas reservoir, and the hydrocarbons include crude oil and/or natural gas. [0009] Some embodiments of the present disclosure pertain to forming the partially sulfonated polymers of the present disclosure. In some embodiments, forming the partially sulfonated polymers involves adding a sulfonate-removing agent to a solution that includes a sulfonated polymer with a plurality of sulfonated monomeric units. In some embodiments, forming the partially sulfonated polymers results in the removal of sulfonate moieties from some of the sulfonated monomeric units. In some embodiments, partially sulfonated polymers form by adding a sulfonating agent to a solution that includes a polymer with a plurality of unsulfonated monomeric units. In some embodiments, forming the partially sulfonated polymers results in the addition of sulfonate moieties to some of the unsulfonated monomeric units. In some embodiments, partially sulfonated polymers form by polymerizing a solution that contains both sulfonated monomeric units and unsulfonated monomeric units. In some embodiments, partially sulfonated polymers form by sequential polymerization of sulfonated monomeric units and unsulfonated monomeric units.

[0010] As set forth in more detail herein, the partially sulfonated polymers and hydrocarbon recovery techniques of the present disclosure are useful in numerous applications. For instance, in some embodiments, the partially sulfonated polymers of the present disclosure may be utilized as chemical additives with detergent-like properties. In some embodiments, the hydrocarbon recovery techniques of the present disclosure may be used for enhanced oil recovery.

BRIEF DESCRIPTION OF THE FIGURES

[0011] FIGURE 1 provides schemes/techniques for recovering hydrocarbons from geological structures by the use of partially sulfonated polymers (FIG. 1A), and techniques for forming the partially sulfonated polymers (FIGS. 1B-E).

[0012] FIGURE 2 shows various structures and schemes relating to the formation of partially desulfonated polystyrene sulfonate ("PDPSS"). FIGS. 2A-B show the molecular structures of polystyrene sulfonate ("PSS") (FIG. 2A) and polystyrene ("PS") (FIG. 2B). FIG. 2C shows a reaction scheme for the formation of PDPSS by the partial desulfonation of PSS. FIG. 2D illustrates a benzene desulfonation mechanism in the presence of an acid at high temperature.

[0013] FIGURE 3 shows possible structures of 50% desulfonated PSS ("50-PDPSS") that are derived from PSS (FIG. 3A), including alternate blocks of 50-PDPSS (FIG. 3B), random blocks of 50-PDPSS (FIG. 3C), and co-polymer blocks of 50-PDPSS (FIG. 3D).

[0014] FIGURE 4 shows a size distribution of a PDPSS sample (referred to as Sample 1 in Example 1) at 25 °C. The hydrodynamic diameters are number- weighed.

[0015] FIGURE 5 shows the hydrodynamic diameter of Sample 1 as a function of temperature, as measured by dynamic light scattering ("DLS"). Diameters are number-weighed.

[0016] FIGURE 6 shows the hydrodynamic diameter of PDPSS clusters formed by partial desulfonation of PSS at 80 °C, 120 °C and 160 °C. The DLS data were collected at 25 °C. The diameters are number-weighed.

[0017] FIGURE 7 shows the hydrodynamic diameter of Sample 1 diluted in API brine (at a final concentration of 0.5 wt %), as measured by DLS as a function of temperature. The diameters are number-weighed. [0018] FIGURE 8 shows the UV-vis absorption spectra of a PSS sample (referred to as Sample 0 in Example 1) and Sample 1. Peaks 1 and 2 correspond to PSS, while peak 3 corresponds to pure polystyrene.

[0019] FIGURE 9 shows images of Sample 0 (FIG. 9A) and Sample 1 (FIG. 9B) after the addition of Nile Red to the samples.

[0020] FIGURE 10 shows images of Sample 0 (FIG. 10A) and Sample 1 (FIG. 10B) after the addition of carbon black to the samples.

[0021] FIGURE 11 shows the diameter of a toluene drop inside a capillary filled with Sample 1 in API brine inside a spinning drop tensiometer.

[0022] FIGURE 12 shows IFT values of Sample 1 in API brine and toluene as a function of time in a spinning drop tensiometer.

[0023] FIGURE 13 shows IFT values of Sample 1 in API brine and toluene in a spinning drop tensiometer at different temperatures.

[0024] FIGURE 14 shows the hydrodynamic diameter of Sample 1 (plot a) and Sample 2 (plot b). Diameters are number- weighed. Sample 2 is a PDPSS polymer with a molecular weight of 1000 kDa. Sample 1 is PDPSS polymer with a molecular weight of 70 kDa.

[0025] FIGURE 15 shows a breakthrough study of Sample 1 (in API brine) in a column filled with Berea sandstone.

[0026] FIGURE 16 shows a breakthrough study of Sample 1 (in API brine) in a column filled with sea sand.

[0027] FIGURE 17 shows the IFT values of PDPSS polymers with oils ranging from highly aromatic (toluene) to highly aliphatic (Isopar-L).

[0028] FIGURE 18 shows schemes of several routes for producing partially sulfonated polymers, including sequential polymerization (FIG. 18A), post-polymerization modification (FIG. 18B), and co- polymerization (FIG. 18C).

DETAILED DESCRIPTION

[0029] It is to be understood that both the foregoing general description and the following detailed description are illustrative and explanatory, and are not restrictive of the subject matter, as claimed. In this application, the use of the singular includes the plural, the word "a" or "an" means "at least one", and the use of "or" means "and/or", unless specifically stated otherwise. Furthermore, the use of the term "including", as well as other forms, such as "includes" and "included", is not limiting. Also, terms such as "element" or "component" encompass both elements or components comprising one unit and elements or components that comprise more than one unit unless specifically stated otherwise. Parameters disclosed herein (e.g., temperature, time, concentrations, etc.) may be approximate.

[0030] The section headings used herein are for organizational purposes and are not to be construed as limiting the subject matter described. All documents, or portions of documents, cited in this application, including, but not limited to, patents, patent applications, articles, books, and treatises, are hereby expressly incorporated herein by reference in their entirety for any purpose. In the event that one or more of the incorporated literature and similar materials defines a term in a manner that contradicts the definition of that term in this application, this application controls.

[0031] A polymer is a compound or a set of compounds formed of repeating monomeric units. The first reported synthetic polymerization was that of styrene in 1839. Since then, a library of polymers such as plastics, rubbers, fibers and similar compounds have been synthesized for various applications.

[0032] For instance, enhanced oil recovery ("EOR") is a technique that has utilized polymers. Typical EOR techniques have included gas injection, chemical injection, seismic stimulation, and microbial injection. One possible method of chemical injection includes the injection of an aqueous injection of surfactants, which either reduces the saturation of the trapped oil by reducing the interfacial tension ("IFT") between the oil and aqueous phase relative to the oil and rock phase, or increases the viscosity of the aqueous phase in order to force out the oil from the rocks. In many instances, hydrophobically modified polymers have been used in EOR in lieu of surfactants.

[0033] Hydrophobically modified polymers are typically fabricated when alkyl moieties are attached to water soluble long chain polymers to impart detergent-like properties on the polymers. Hydrophobically modified polymers have been prepared by micellar polymerization, where copolymers of the hydrophobically modified units are randomly distributed as small blocks in the parent polymer chain. Common examples of such hydrophobically modified polymers are polyacrylamides and polysaccharides. Since such polymers lower the oil/water interfacial tension, they may be useful in enhanced oil recovery from oil reservoirs that utilize a water flooding medium.

[0034] Additional polymers that have been deemed suitable for use in EOR have included water- soluble polymers disclosed in EP 2348089A1 ("the '089 application"). In particular, the '089 application discloses water-soluble anionic polymer from a vinyl monomer which is partially or fully neutralized by an organic counter-ion. A general formula for such polymers in the '089 application is - NHR_!R₂R₃, where R includes H, Ci-Ci₀ alkyl, C₃-C₈ cycloalkyl, C₆-C-i₄ aryl, heteroaryl and polyoxoethylene groups.

[0035] The '089 application also discloses high molecular weight water soluble polymers that contain at least one non-ionic monomer and at least one amphiphillic monomer with a side chain that has a hydrophilic-to-lipophilic balance (HLB) of more than 4.5. The non-ionic monomers in the '089 application include acrylamides and vinyl monomers. Likewise, the amphiphillic monomers in the '089 application include (meth)acrylamide, (meth)acrylic, vinyl, allyl or maleic backbones with alkyl or arylalkyl side groups that contain at least one heteroatom.

[0036] However, many of the previously disclosed polymers that are utilized for enhanced oil recovery (including hydrophobically modified polymers) have poor mobility through underground reservoirs. Therefore, such polymers can lead to plugging of the porous rocks. Such plugging can in turn trap oil inside those rocks.

[0037] In addition, polymers such as polysaccharides are prone to be hydrolyzed in the presence of water. Likewise, many polymers such as polyacrylamides are prone to disintegrate in the presence of shear forces. Such limitations can in turn affect the efficacy of the polymers in oil recovery.

[0038] Polystyrene sulfonate ("PSS") may be useful for use in enhanced oil recovery. In particular, PSS costs less than other hydrophobically modified polymers (e.g., Xanthan gum) due to its efficient synthesis by copolymerization of styrene sulfonate. However, PSS is not stable at high temperatures. In particular, PSS can decompose to SO_x and Na₂0 fumes. In addition, PSS does not have detergentlike properties. Therefore, PSS may be limited for applications in enhanced oil recovery.

[0039] As such, there is a desire for affordable detergent-like polymers that are chemically stable and non-reactive at high temperature and high salinity conditions for various applications, including enhanced oil recovery. Moreover, there is a desire for efficient methods of forming such polymers. The present disclosure provides solutions for addressing these issues.

[0040] Partially Sulfonated Polymers

[0041] Partially sulfonated polymers generally refer to polymers that contain both sulfonated and unsulfonated monomeric units. In particular, the partially sulfonated polymers of the present disclosure include a polymer chain with a plurality of monomeric units. The monomeric units include both sulfonated monomeric units that are associated with sulfonate moieties, and unsulfonated monomeric units that lack the sulfonate moieties. As set forth in more detail herein, the partially sulfonated polymers of the present disclosure may contain various polymer chains, sulfonated monomeric units, sulfonate moieties, and unsulfonated monomeric units. Moreover, the monomeric units of the present disclosure can have various arrangements within the polymer chains. In addition, the partially sulfonated polymers of the present disclosure can have various shapes and properties.

[0042] Polymer chains

[0043] The partially sulfonated polymers of the present disclosure may include various polymer chains. In some embodiments, the polymer chains may include, without limitation, sulfonated poly(vinyl alcohol), sulfonated polyurethane, sulfonated poly(ethylene glycol), sulfonated poly(propylene glycol), sulfonated poly(ethylene imine), sulfonated sorbitol, sulfonated polysaccharides, sulfonated polylactone, sulfonated polyacrylates, sulfonated polyacrylonitrile, sulfonated polyethylene, sulfonated polyvinyls, sulfonated poly( vinyl chloride), sulfonated polyacrylamides, sulfonated poly(acrylic acid), sulfonated polystyrene, sulfonated high impact polystyrene, sulfonated polypropylene, sulfonated polyester, sulfonated poly(hydroxyalkyl ester), sulfonated poly (butadiene) vinyl polymers, and combinations thereof.

[0044] In some embodiments, the polymer chain of the partially sulfonated polymers includes sulfonated polystyrene. In some embodiments, the sulfonated polystyrene is poly[sodium 4- styrenesulfonate] . Additional polymer chains can also be believed.

[0045] Sulfonated monomeric units

[0046] The polymer chains of the present disclosure may include various sulfonated monomeric units. In some embodiments, the sulfonated monomeric units include, without limitation, sulfonated vinyl alcohols, sulfonated urethanes, sulfonated ethylene glycol, sulfonated propylene glycol, sulfonated ethylene imine, sulfonated saccharides, sulfonated lactone, sulfonated acrylates, sulfonated acrylonitrile, sulfonated ethylene, sulfonated vinyls, sulfonated vinyl chloride, sulfonated acrylamides, sulfonated acrylic acid, sulfonated styrene, sulfonated propylene, sulfonated hydroxyalkyl ester, sulfonated butadiene, and combinations thereof.

[0047] In some embodiments, the sulfonated monomeric units of the present disclosure include sulfonated styrenes. In some embodiments, the sulfonated styrenes include 4-styrene sulfonic acid. In some embodiments, the sulfonated styrenes include styrene sulfonate neopentyl ester. [0048] In some embodiments, the sulfonated monomeric units of the present disclosure include sulfonated acrylic acids. In some embodiments, the sulfonated acrylic acids include 2-acrylamido-2- methylpropane sulfonic acid.

[0049] In some embodiments, the sulfonated monomeric units of the present disclosure include acrylic acids. In some embodiments, the acrylic acids include 2-acrylamido-2-methylpropane sulfonic acid.

[0050] In some embodiments, the sulfonated monomeric units of the present disclosure include sulfonated vinyls. In some embodiments, the sulfonated vinyls include, without limitation, vinyl sulfonate, sulfonated vinyl alcohols, and combinations thereof.

[0051] In some embodiments, the sulfonated monomeric units of the present disclosure include sulfonated ethylene glycols. In some embodiments, the sulfonated ethylene glycols include, without limitation, sulfonated polyethylene glycol acrylate, sulfonated polyethylene glycol methacrylate, and combinations thereof.

[0052] In some embodiments, the sulfonated monomeric units of the present disclosure include sulfonated propylenes. In some embodiments, the sulfonated propylenes include propylene sulfonates.

[0053] The sulfonated monomeric units of the present disclosure are associated with one or more sulfonate moieties. In some embodiments, the sulfonated monomeric units are covalently associated with sulfonate moieties. In some embodiments, the sulfonated monomeric units are non-covalently associated with sulfonate moieties.

[0054] In some embodiments, the sulfonate moieties that are associated with a sulfonated monomeric unit include the following chemical formula:

-SO₃R

[0055] In some embodiments, R includes, without limitation, H, Na, K, Li, NH₄, alkyl groups, aryl groups, phenyl groups, and combinations thereof. In some embodiments, R is Na.

[0056] In some embodiments, the sulfonated monomeric units are hydrophilic. In some embodiments, the sulfonated monomeric units are derived from unsulfonated monomeric units. For instance, in some embodiments that will be described in more detail herein, sulfonated monomeric units can be produced on polymer chains by the sulfonation of unsulfonated monomeric units.

[0057] Unsulfonated monomeric units

[0058] The polymer chains of the present disclosure may also include various unsulfonated monomeric units. In some embodiments, the unsulfonated monomeric units include, without limitation, vinyl alcohols, urethanes, ethylene glycol, propylene glycol, ethylene imine, saccharides, lactone, acrylates, acrylonitrile, ethylene, vinyls, vinyl chloride, acrylamides, acrylic acid, styrene, propylene, hydroxyalkyl ester, butadiene, and combinations thereof.

[0059] In some embodiments, the unsulfonated monomeric units of the present disclosure include styrenes. In some embodiments, the styrenes include alkyl styrenes. In some embodiments, the alkyl styrenes include, without limitation, 4-(teri-butyl styrene), methyl styrene, chloromethyl styrene, and combinations thereof. [0060] In some embodiments, the monomeric units of the present disclosure include vinyls. In some embodiments, the vinyls include, without limitation, vinyl pyridine, vinyl alcohols, and combinations thereof.

[0061] In some embodiments, the monomeric units of the present disclosure include acrylic acids. In some embodiments, the acrylic acids include methacrylic acid.

[0062] In some embodiments, the monomeric units of the present disclosure include acrylates. In some embodiments, the acrylates include, without limitation, methacrylates, methyl acrylate, methyl methacrylate, hydroxyethyl acrylate, lauryl acrylate, lauryl methacrylate, oligo- or polyethylene glycol acrylate, oligo- or polyethylene glycol methacrylate, and combinations thereof.

[0063] The polymer chains of the present disclosure may include various amounts of unsulfonated monomeric units. For instance, in some embodiments, the unsulfonated monomeric include more than about 5% of the monomeric units of the polymer chain. In some embodiments, the unsulfonated monomeric units include between about 5% to about 90% of the monomeric units of the polymer chain. In some embodiments, the unsulfonated monomeric units include between about 5% to about 40% of the monomeric units of the polymer chain. In some embodiments, the unsulfonated monomeric units include about 10% of the monomeric units of the polymer chain. In some embodiments, the unsulfonated monomeric units include about 35% of the monomeric units of the polymer chain. In some embodiments, the unsulfonated monomeric units include about 50% of the monomeric units of the polymer chain. In some embodiments, the unsulfonated monomeric units include less than about 100% of the monomeric units of the polymer chain.

[0064] In some embodiments, the unsulfonated monomeric units are hydrophobic. In some embodiments, the unsulfonated monomeric units are derived from sulfonated monomeric units. For instance, in some embodiments that will be described in more detail herein, unsulfonated monomeric units are produced on polymer chains by the desulfonation of sulfonated monomeric units. In some embodiments, such unsulfonated monomeric units may be referred to as desulfonated monomeric units. Likewise, the partially sulfonated polymers that contain such desulfonated monomeric units may be referred to as partially desulfonated polymers.

[0065] Monomeric unit arrangements

[0066] The monomeric units of the present disclosure may have various arrangements within polymer chains. In some embodiments, the sulfonated monomeric units and the unsulfonated monomeric units are randomly arranged within a polymer chain. In some embodiments, the sulfonated monomeric units and the unsulfonated monomeric units are randomly distributed as small blocks in a polymer chain.

[0067] In some embodiments, the sulfonated monomeric units and the unsulfonated monomeric units may be arranged in an orderly manner within a polymer chain. For instance, in some embodiments, the sulfonated monomeric units and the unsulfonated monomeric units are arranged in alternate blocks within a polymer chain.

[0068] Shapes

[0069] The partially sulfonated polymers of the present disclosure may have various shapes. For instance, in some embodiments, the partially sulfonated polymers of the present disclosure include a spherical shape. In some embodiments, the partially sulfonated polymers of the present disclosure are in the form of a cluster. [0070] In some embodiments, the partially sulfonated polymers of the present disclosure have a spherical shape that includes a hydrophobic inner core and a hydrophilic outer surface. In some embodiments, the hydrophobic inner core includes unsulfonated monomeric units, and the hydrophilic outer surface includes sulfonated monomeric units.

[0071] The partially sulfonated polymers of the present disclosure may also have various sizes. For instance, in some embodiments, the partially sulfonated polymers of the present disclosure have diameters that range from about 4 nm to about 150 nm. In some embodiments, the partially sulfonated polymers of the present disclosure have diameters that range from about 75 nm to about 150 nm. In some embodiments, the partially sulfonated polymers of the present disclosure have diameters of about 110 nm. In some embodiments, the partially sulfonated polymers of the present disclosure include diameters that range from about 4 nm to about 8 nm. In some embodiments, the partially sulfonated polymers of the present disclosure include diameters that range from about 7 nm to about 8 nm. In some embodiments, the partially sulfonated polymers of the present disclosure include diameters of about 7.5 nm.

[0072] In some embodiments, the diameters of the partially sulfonated polymers of the present disclosure are stable. For instance, in some embodiments, the diameters of the partially sulfonated polymers of the present disclosure do not fluctuate substantially with temperature and/or time.

[0073] The partially sulfonated polymers of the present disclosure may also have various molecular weights. For instance, in some embodiments, the partially sulfonated polymers of the present disclosure have molecular weights that range from about 1 kDa to about 1000 kDa. In some embodiments, the partially sulfonated polymers of the present disclosure have molecular weights that range from about 10 kDa to about 500 kDa. In some embodiments, the partially sulfonated polymers of the present disclosure have molecular weights that range from about 100 kDa to about 1,000 kDa.

[0074] Properties

[0075] The partially sulfonated polymers of the present disclosure may have various properties. For instance, in some embodiments, the partially sulfonated polymers of the present disclosure have an interfacial tension ("IFT") that ranges from about 1 x 10^"2 dyne/cm to about 10 x 10^"2 dyne/cm. In some embodiments, the partially sulfonated polymers of the present disclosure have an IFT that ranges from about 1.5 x 10^"2 dyne/cm to about 2.5 x 10^"2 dyne/cm. In some embodiments, the partially sulfonated polymers of the present disclosure have an IFT of about 2 x 10^"2 dyne/cm. In some embodiments, the partially sulfonated polymers of the present disclosure have an IFT that ranges from about 8 x 10^"2 dyne/cm to about 9 x 10^"2 dyne/cm. In some embodiments, the partially sulfonated polymers of the present disclosure have an IFT of about 2 x 10^"2 dyne/cm.

[0076] In some embodiments, the IFT values of the partially sulfonated polymers of the present disclosure are stable. For instance, in some embodiments, the IFT values of the partially sulfonated polymers of the present disclosure do not fluctuate substantially with temperature and/or time.

[0077] In some embodiments, the partially sulfonated polymers of the present disclosure have a hydrophilic -lipophilic balance ("HLB") that ranges from about 5 to about 20. In some embodiments, the partially sulfonated polymers of the present disclosure have an HLB that ranges from about 5 to about 15. In some embodiments, the partially sulfonated polymers of the present disclosure have an HLB that ranges from about 5 to about 10. [0078] Recovery of Hydrocarbons from Geological Structures

[0079] Some embodiments of the present disclosure pertain to recovering hydrocarbons from a geological structure by utilizing the partially sulfonated polymers of the present disclosure. Some embodiments of the present disclosure may be utilized for enhanced oil recovery ("EOR"). In some embodiments that are illustrated in FIG. 1A, recovering hydrocarbons and/or EOR involve injecting a composition into a geological structure, where the composition includes partially sulfonated polymers of the present disclosure (block 10); and collecting the composition after flow through the geological structure (block 12). In some embodiments, the flow results in association of the hydrocarbons in the geological structure with the composition. Some embodiments of the present disclosure also include separating recovered hydrocarbons from the composition (block 14).

[0080] As set forth in more detail herein, various compositions may be utilized to recover various types of hydrocarbons from various geological structures. In addition, various techniques may be utilized to inject and collect the compositions of the present disclosure from the geological structures. In addition, various techniques may be utilized to separate recovered hydrocarbons from a composition.

[0081] Compositions

[0082] Compositions utilized for the recovery of hydrocarbons from a geological structure generally include one or more partially sulfonated polymers of the present disclosure. For instance, in some embodiments, the compositions of the present disclosure include a partially sulfonated polymer with a polymer chain that includes a plurality of sulfonated monomeric units and unsulfonated monomeric units. In some embodiments, partially sulfonated polymers in the compositions of the present disclosure include partially sulfonated polystyrene.

[0083] In some embodiments, the partially sulfonated polymers of the present disclosure constitute from about 1% to about 25% of the composition by weight. In some embodiments, the partially sulfonated polymers of the present disclosure constitute from about 5% to about 15% of the composition by weight. In some embodiments, the partially sulfonated polymers of the present disclosure constitute from about 5% to about 10% of the composition by weight.

[0084] The compositions of the present disclosure may also have additional components. For instance, in some embodiments, the compositions of the present disclosure include saltwater. In some embodiments, the compositions of the present disclosure include brine. In some embodiments, the compositions of the present disclosure include one or more surfactants. In some embodiments, the surfactants include, without limitation, petroleum-based surfactants, alkali surfactants, cationic surfactants, and combinations thereof.

[0085] Geological Structures

[0086] The compositions of the present disclosure may be injected into various geological structures. For instance, in some embodiments, the geological structure is an underground reservoir. In some embodiments, the geological structure is an oil and/or gas reservoir. In some embodiments, the geological structure is a subterranean formation that contains various stones and sands, such as Berea sandstone and sea sand. In some embodiments, the geological structure is an oil-contaminated water aquifer. In some embodiments, the geological structure is a hydrocarbon reservoir. In some embodiments, the geological structure is an oil and/or gas well. [0087] Injection and Collection of Compositions

[0088] Various techniques may be utilized to inject compositions into geological structures. For instance, in some embodiments, the injecting occurs by pumping a composition into the geological structure. In some embodiments, the pumping occurs by the utilization of a pump.

[0089] Various techniques may also be utilized to collect compositions from a geological structure after flow through the geological structure. For instance, in some embodiments, the collecting occurs by drawing out the composition from a geological structure. In some embodiments, the drawing out occurs by the use of a pump. In some embodiments, the collecting occurs manually by recovering the composition as it flows out of a geological structure.

[0090] In some embodiments, the compositions of the present disclosure are injected into a first location of a geological structure and collected from a second location of the geological structure. For instance, in some embodiments, the first location is an injection well, and the second location is a production well. In some embodiments, the injecting and the collecting occur from a single location (e.g., a wellbore) in a geological structure.

[0091] Hydrocarbons

[0092] Embodiments of the present disclosure may be utilized to recover various types of hydrocarbons from a geological structure. For instance, in some embodiments, the hydrocarbons include crude oil. In some embodiments, the hydrocarbons include, without limitation, aromatic hydrocarbons, aliphatic hydrocarbons, alkanes, alkenes, alkynes, and combinations thereof.

[0093] The compositions of the present disclosure may associate with hydrocarbons in various manners. For instance, in some embodiments, the association occurs through the formation of a suspension between the hydrocarbons and the composition. In some embodiments, the suspension may be in the form of an emulsion or dispersion. In some embodiments, the association occurs through the formation of a solution. In some embodiments, the solution is a homogenous solution that contains hydrocarbons dissolved in the composition.

[0094] Without being bound by theory, it is believed that partially sulfonated polymers of the present disclosure facilitate the association of hydrocarbons with the compositions of the present disclosure. For instance, in some embodiments, partially sulfonated polymers in the compositions of the present disclosure reduce the saturation of trapped hydrocarbons by reducing the interfacial tension ("IFT") between the hydrocarbons and the composition relative to the hydrocarbons and a rock phase. In some embodiments, the partially sulfonated polymers in the compositions of the present disclosure also force out the hydrocarbons from the rocks in the geological structures.

[0095] Separation of hydrocarbons from compositions

[0096] Some embodiments of the present disclosure also include separating recovered hydrocarbons from a composition. Various techniques may be utilized to separate recovered hydrocarbons from compositions. For instance, in some embodiments, the separation occurs by centrifugation, filtration, distillation, extraction, and combinations thereof. In some embodiments, the separation occurs by centrifugation. Additional separation techniques can also be envisioned. [0097] Forming Partially Sulfonated Polymers

[0098] Various techniques may be utilized to form the partially sulfonated polymers of the present disclosure. As described in more detail herein and illustrated in FIGS. 1B-E, such techniques include the removal of sulfonate moieties from sulfonated monomeric units of sulfonated polymers (FIG. IB), addition of sulfonated moieties to monomeric units of polymers (FIG. 1C), polymerization of a solution containing unsulfonated and sulfonated monomeric units (FIG. ID), and sequential polymerization of unsulfonated monomeric units and sulfonated monomeric units (FIG. IE).

[0099] Removal of sulfonate moieties from sulfonated polymers

[00100] In some embodiments that are illustrated in FIG. IB, the partially sulfonated polymers of the present disclosure are formed by adding a sulfonate-removing agent to a solution that includes a sulfonated polymer (block 30). The sulfonated polymer contains a plurality of sulfonated monomeric units with sulfonate moieties. This may result in removal of sulfonate moieties from some of the sulfonated monomeric units to form unsulfonated monomeric units. Some embodiments may also include heating the solution (block 32). Some embodiments may also include cooling the solution (block 34).

[00101] Various sulfonated polymers may be utilized to form partially sulfonated polymers. For instance, in some embodiments, the sulfonated polymers include, without limitation, sulfonated poly(vinyl alcohol), sulfonated polyurethane, sulfonated poly(ethylene glycol), sulfonated poly(propylene glycol), sulfonated poly(ethylene imine), sulfonated sorbitol, sulfonated polysaccharides, sulfonated polylactone, sulfonated polyacrylates, sulfonated polyacrylonitrile, sulfonated polyethylene, sulfonated polyvinyls, sulfonated poly( vinyl chloride), sulfonated polyacrylamides, sulfonated poly(acrylic acid), sulfonated polystyrene, sulfonated high impact polystyrene, sulfonated polypropylene, sulfonated polyester, sulfonated poly(hydroxyalkyl ester), sulfonated poly(butadiene), sulfonated vinyl polymers, and combinations thereof. In some embodiments, the sulfonated polymers include sulfonated polystyrene. In some embodiments, each of the monomeric units of the sulfonated polymers is sulfonated.

[00102] The sulfonated polymers of the present disclosure may be in various solutions. For instance, in some embodiments, the solution includes, without limitation, water, formic acid, toluene, dichloromethane, dimethylformamide, and combinations thereof. In some embodiments, the solution includes water.

[00103] In addition, various sulfonate-removing agents may be added to a solution that includes a sulfonated polymer. For instance, in some embodiments, the sulfonate-removing agent may include, without limitation, hydrochloric acid, hydrofluoric acid, hydroiodic acid, hydrobromic acid, and combinations thereof. In some embodiments, the sulfonate-removing agent is hydrochloric acid.

[00104] Various techniques may also be utilized to add a sulfonate-removing agent to a solution that contains a sulfonated polymer. For instance, in some embodiments, the adding includes mixing the sulfonated polymer with the sulfonate-removing agent. In some embodiments, the mixing may involve physical agitation. In some embodiments, the mixing may involve sonication. Additional techniques of adding a sulfonate-removing agent to a solution that contains a sulfonated polymer can also be envisioned.

[00105] In some embodiments, the adding of the sulfonate-removing agent to a solution lowers the pH of the solution. For instance, in some embodiments, the pH of the solution is lowered to about 2. In some embodiments, the pH of the solution is lowered to about 1. In some embodiments, the pH of the solution is lowered to about 0.4 to about 2. In some embodiments, the pH of the solution is lowered to about 0.9 to about 1.2.

[00106] Some embodiments of the present disclosure also include heating a solution that contains sulfonated polymers and sulfonate -removing agents. In some embodiments, the heating occurs after adding a sulfonate -removing agent to the solution. In some embodiments, the solution is heated to temperatures between about 80 °C and about 200 °C. In some embodiments, the solution is heated to temperatures between about 80 °C and about 160 °C. In some embodiments, the solution is heated to a temperature of about 160 °C.

[00107] In some embodiments, a solution containing sulfonated polymers and sulfonate-removing agents is heated by microwave heating. In some embodiments, the solution is heated by microwave hearting to temperatures of about 160 °C.

[00108] Solutions that contain sulfonated polymers and sulfonate-removing agents may be heated for various periods of time. For instance, in some embodiments, the heating occurs for about 10 seconds to about 5 minutes. In some embodiments, the heating occurs for less than about 30 seconds. In some embodiments, the heating occurs for less than about 60 seconds. In some embodiments, the heating occurs for less than about 5 minutes.

[00109] Some embodiments of the present disclosure may also include a cooling of a solution. For instance, in some embodiments, a solution may be cooled after it has been heated. In some embodiments, the solution is cooled to temperatures that range from about 50 °C to about 25 °C. In some embodiments, the solution is cooled to about 25 °C.

[00110] Addition of sulfonate moieties to polymers

[00111] In some embodiments that are illustrated in FIG. 1C, the partially sulfonated polymers of the present disclosure are formed by adding a sulfonating agent to a solution that includes a polymer with a plurality of unsulfonated monomeric units (block 40). This may result in addition of sulfonate moieties to some of the unsulfonated monomeric units. Some embodiments also include heating the solution (block 42). Some embodiments also include cooling the solution (block 44).

[00112] Various polymers may be utilized to form partially sulfonated polymers. For instance, in some embodiments, the polymers may include, without limitation, poly(vinyl alcohol), polyurethane, poly(ethylene glycol), poly(propylene glycol), poly(ethylene imine), sorbitol, polysaccharides, polylactone, polyacrylates, polyacrylonitrile, polyethylene, polyvinyls, poly(vinyl chloride), polyacrylamides, poly(acrylic acid), polystyrene, high impact polystyrene, polypropylene, polyester, poly(hydroxyalkyl ester), poly (butadiene) vinyl polymers, and combinations thereof. In some embodiments, the polymers include polystyrene. In some embodiments, each of the monomeric units of the unsulfonated polymers is unsulfonated.

[00113] The polymers of the present disclosure may be in various solutions. For instance, in some embodiments, the solution includes, without limitation, water, formic acid, toluene, dichloromethane, dimethylformamide, and combinations thereof. In some embodiments, the solution includes water.

[00114] In addition, various sulfonating agents may be added to a solution that includes a polymer. For instance, in some embodiments, the sulfonating agent may include, without limitation, sulfuric acid, sodium bisulfite, sulfur trioxide, sulfamic acid, chlorosulfonic acid, and combinations thereof. In some embodiments, the sulfonating agent is sulfuric acid.

[00115] Various techniques may also be utilized to add a sulfonating agent to a solution that contains a polymer. For instance, in some embodiments, the adding includes mixing the polymer with the sulfonating agent. In some embodiments, the mixing may involve physical agitation or sonication. Additional techniques of adding a sulfonating agent to a solution that contains a polymer can also be envisioned.

[00116] Some embodiments of the present disclosure also include heating a solution that contains polymers and sulfonating agents. In some embodiments, the heating occurs after adding a sulfonating agent to the solution. In some embodiments, the solution is heated to temperatures between about 80 °C and about 200 °C. In some embodiments, the solution is heated to temperatures between about 80 °C and about 160 °C. In some embodiments, the solution is heated to a temperature of about 160 °C. In some embodiments, the solution is heated by microwave heating. In some embodiments, the solution is heated by microwave heating to temperatures of about 160 °C.

[00117] In some embodiments, the heating occurs for about 10 seconds to about 5 minutes. In some embodiments, the heating occurs for less than about 30 seconds. In some embodiments, the heating occurs for less than about 60 seconds. In some embodiments, the heating occurs for less than about 5 minutes.

[00118] Some embodiments of the present disclosure may also include cooling of a solution. For instance, in some embodiments, a solution may be cooled after it has been heated. In some embodiments, the solution is cooled to temperatures that range from about 50 °C to about 25 °C. In some embodiments, the solution is cooled to about 25 °C.

[00119] Polymerization of unsulfonated and sulfonated monomeric units

[00120] Some embodiments for forming partially sulfonated polymers involve the polymerization of unsulfonated and sulfonated monomeric units. For instance, as illustrated in FIG. ID, some embodiments for forming partially sulfonated polymers involve adding a polymerizing agent to a solution that includes unsulfonated monomeric units and sulfonated monomeric units (block 50). This may result in polymerization of the unsulfonated monomeric units with the sulfonated monomeric units to form the partially sulfonated polymers of the present disclosure. Some embodiments may also include heating the solution (block 52). Some embodiments may also include cooling the solution (block 54).

[00121] Various polymerizing agents may be added to solutions that contain unsulfonated monomeric units and sulfonated monomeric units. For instance, in some embodiments, the polymerizing agent includes, without limitation, azobisisobutyronitrile, l,l'-Azobis(cyclohexanecarbonitrile), di-tert-butyl peroxide, benzoyl peroxide, methyl ethyl ketone peroxide, peroxydisulfate salts, copper chelates, alkyl or aryl lithium reagents, alkyl or aryl sodium reagents, alkyl or aryl potassium reagents, and combinations thereof. In some embodiments, the polymerizing agent contains a copper chelate with the following formula: CuX₂/Ligands, where X is CI or Br.

[00122] In some embodiments, the unsulfonated monomeric units and sulfonated monomeric units may be added to a solution to form a homogeneous solution. In some embodiments, the unsulfonated monomeric units and sulfonated monomeric units may form a heterogeneous mixture, such as emulsions, mini-emulsions, micro-emulsions, bi- and tri-phasic mixtures, and combinations thereof. [00123] Heating may occur at various temperatures. For instance, in some embodiments, heating occurs at temperatures between about 50 °C and about 110 °C. In some embodiments, a solution may be de-oxygenated prior to heating.

[00124] The unsulfonated and sulfonated monomeric units of the present disclosure may be dissolved in various solutions. For instance, in some embodiments, the unsulfonated and sulfonated monomeric units are dissolved in organic or aqueous solutions at concentrations between 0.1 M and 5 M. In some embodiments, the unsulfonated and sulfonated monomeric units may be polymerized in the absence of a solvent.

[00125] In some embodiments, the methods of the present disclosure also include a step of adding additional portions of sulfonated monomeric units or unsulfonated monomeric units. In some embodiments, the methods of the present disclosure also include a step of changing a feed ratio of the sulfonated monomeric units and unsulfonated monomeric units during polymerization. For instance, in some embodiments, the feed molar ratio of unsulfonated monomeric units to sulfonated monomeric units may vary from about 0.1:1 to about 1:0.1. In some embodiments, the feed molar ratio of unsulfonated monomeric units to sulfonated monomeric units may be about 1:1, 1:2, 1:3, 2:1, or 3:1.

[00126] Various unsulfonated and sulfonated monomeric units may be utilized to form partially sulfonated polymers through polymerization. Suitable examples include the unsulfonated and sulfonated monomeric units of the present disclosure.

[00127] In some embodiments, unsulfonated monomeric units that may be utilized to form partially sulfonated polymers through polymerization may include, without limitation, styrene, 4-(ieri-butyl styrene), methyl styrene, chloromethyl styrene, vinyl pyridine, vinyl alcohols, acrylates, methacrylates, methyl acrylate, methyl methacrylate, hydroxyethyl acrylate, lauryl acrylate, lauryl methacrylate, oligo- or polyethylene glycol acrylate, oligo- or polyethylene glycol methacrylate, acrylonitriles, acrylamides, acrylic acid, methacrylic acid, and combinations thereof. In some embodiments, sulfonated monomeric units that may be utilized to form partially sulfonated polymers through polymerization may include, without limitation, 2-acrylamido-2-methylpropane sulfonic acid, 4-styrene sulfonic acid, vinyl sulfonate, sulfonated polyethylene glycol methacrylate, sulfonated polyethylene glycol acrylate, sulfonated vinyl alcohols, sulfonated urethanes, sulfonated ethylene imine, sulfonated saccharides, sulfonated lactone, sulfonated acrylonitrile, sulfonated vinyls, sulfonated acrylamides, propylene sulfonates, sulfonated hydroxy alkyl esters, sulfonated butadienes, and combinations thereof. In some embodiments, the sulfonated monomeric units include sulfonated styrene or styrene sulfonate neopentyl ester.

[00128] Sequential polymerization

[00129] Some embodiments for forming partially sulfonated polymers involve the sequential polymerization of unsulfonated and sulfonated monomeric units. For instance, in some embodiments, as illustrated in FIG. IE, a solution containing unsulfonated monomeric units is polymerized to form an unsulfonated polymer (block 60). Thereafter, sulfonated monomeric units are added to the solution (block 62). A subsequent polymerization (block 64) is then carried out to couple the sulfonated monomeric units to the unsulfonated polymer.

[00130] In some embodiments, a solution containing sulfonated monomeric units is first polymerized to form a sulfonated polymer. Thereafter, unsulfonated monomeric units are added to the solution. A subsequent polymerization is then carried out to couple the unsulfonated monomeric units to the sulfonated polymer. [00131] In some embodiments, the solution containing monomeric units and polymers may be substituted with a solvent-free mixture. In some embodiments, a formed polymer may be isolated and purified prior to addition of monomeric units.

[00132] Heating may occur at various temperatures. For instance, in some embodiments, the solution is heated to temperatures between about 50°C and 110 °C. In some embodiments, the solution is de- oxygenated prior to heating.

[00133] Various unsulfonated and sulfonated monomeric units may be utilized to form partially sulfonated polymers through sequential polymerization. Suitable examples include the unsulfonated and sulfonated monomeric units of the present disclosure.

[00134] In some embodiments, suitable unsulfonated monomeric units that may be utilized to form partially sulfonated polymers through sequential polymerization may include, without limitation, vinyl alcohols, urethanes, ethylene glycol, propylene glycol, ethylene imine, saccharides, lactone, acrylonitriles, acrylates, methacrylates, vinyl chloride, acrylamides, acrylic acids, styrene, alkyl styrenes, hydroxy alkyl esters, butadienes, and combinations thereof. In some embodiments, the unsulfonated monomeric units include styrene. In some embodiments, suitable sulfonated monomeric units that may be utilized to form partially sulfonated polymers through sequential polymerization may include, without limitation, sulfonated vinyl alcohols, sulfonated urethanes, sulfonated ethylene glycol, sulfonated propylene glycol, sulfonated ethylene imine, sulfonated saccharides, sulfonated lactone, sulfonated acrylonitrile, sulfonated ethylene, sulfonated vinyls, sulfonated vinyl chloride, sulfonated acrylamides, sulfonated acrylic acid, sulfonated styrene, sulfonated propylene, sulfonated hydroxyalkyl ester, sulfonated butadiene, and combinations thereof. In some embodiments, the sulfonated monomeric units include sulfonated styrene.

[00135] Applications and Advantages

[00136] Partially sulfonated polymers of the present disclosure demonstrate stability in high temperature and high salinity environments. In addition, partially sulfonated polymers of the present disclosure have surfactant-like properties. Moreover, some embodiments of the present disclosure may be utilized to make partially sulfonated polymers in an efficient and cost effective manner. As such, the partially sulfonated polymers of the present disclosure may find numerous applications.

[00137] For instance, in some embodiments, the partially sulfonated polymers of the present disclosure may be utilized as chemical additives for lowering the interfacial tension between an oil phase and a carrier water phase. In some embodiments, the partially sulfonated polymers of the present disclosure may be utilized as viscosity modifying agents in conjunction with other surfactants, such as cationic surfactants. In some embodiments, partially sulfonated polymer-surfactant mixtures may be used to control the mixture's rheological properties in fluids and thereby aid in the formation of stable emulsions that would otherwise not be possible by surfactants alone. In some embodiments, partially sulfonated polymer-surfactant mixtures may be used as drilling fluids.

[00138] As set forth previously, the partially sulfonated polymers of the present disclosure may also be utilized as chemical additives for enhanced oil recovery. In some embodiments, the partially sulfonated polymers of the present disclosure may also be utilized for environmental remediation. For instance, in some embodiments, the partially sulfonated polymers of the present disclosure may be used for the removal of oil deposits found in contaminated water aquifers. In some embodiments, the partially sulfonated polymers of the present disclosure may be used as substitutes for surfactant molecules and other materials with detergent-like properties. [00139] Reference will now be made to various embodiments of the present disclosure and experimental results that provide support for such embodiments. However, the following disclosure is for illustrative purposes only and is not intended to limit the scope of the claimed subject matter in any way.

[00140] Example 1. Preparation and Characterization of Partially Desulfonated Polystyrene Sulfonate

[00141] This Example discloses a general approach to prepare partially desulfonated polystyrene sulfonate ("PDPSS") with detergent-like properties. The approach in this Example is based on a controlled desulfonation of polystyrene sulfonate ("PSS"). The properties and applications of the produced PDPSS polymers are also evaluated in this Example.

[00142] PSS, as purchased commercially or prepared through polymerization of styrene sulfonated monomers, is 100% sulfonated. In other words, each monomeric unit of PSS is attached to a sulfonated group, as illustrated in FIG. 2A. However, PDPSS is less than 100% sulfonated. Moreover, as illustrated in FIG. 2B, polystyrene ("PS") is 0% sulfonated.

[00143] As illustrated in FIG. 2C, the controlled desulfonation of PSS (in this case poly[sodium 4- styrenesulfonate]) can occur by exposure of PSS to an acidic environment at high temperatures. Without being bound by theory, it is believed that some of the monomer units lose the hydrophilic S0₃ ^" Na⁺ groups as a result of desulfonation. This can in turn cause the polymer to bring the remaining S0₃ ^" Na⁺ groups that extend into the water phase and the styrene groups close to each other. As a result, the desulfonation leads to the formation of a soft nanoparticle-like structure. Without again being bound by theory, it is believed that the mechanism of desulfonation of PSS is based on the desulfonation of benzenesulfonic acid, as depicted in FIG. 2D.

[00144] Example 1.1. Preparation of PDPSS polymers

[00145] A 5 wt% solution of PSS (with an average molecular weight of 70,000 Da) in deionized water ("DI H₂0") was prepared. Next, a stock solution of 30 wt% HC1 was added to the solution in order to lower the pH of the solution to a value of 1 and thereby maintain the solution's ionic strength at 0.1 M. Next, the solution was rapidly heated to 160 °C (e.g., in a microwave reactor (Anton Paar Monowave 300, 850 W microwave power)) and maintained at that temperature for about 30 minutes before cooling down to room temperature.

[00146] The mechanism of desulfonation of styrene is well understood and depicted in FIG. 2D. Depending on the nature of desulfonation, the product could have a random arrangement of sulfonated and desulfonated monomer units or be similar to a surfactant with a continuous block of sulfonated monomer units followed by a continuous block of desulfonated monomer units, or any combination in between, as illustrated in FIG. 3. In particular, FIG. 3 shows some possible structures of PDPSS, including molecular structures for a polymer of similar molecular weight but with different arrangements of hydrophilic (i.e., sulfonated) and hydrophobic (i.e., desulfonated) units (FIGS. 3B-D). In various embodiments, the actual solution may be a mixture of these structures.

[00147] A commonly used metric in relating the molecular structure of a surfactant to a particular surface-active property is the hydrophilic -lipophilic balance ("HLB"), as shown in Equation 1 below and defined by Griffin (Am. Perfumer Essent. Oil Re. , 1955. 65: 26-29): HLB = 20 (Mh/M) (1)

[00148] In this equation, Mh is the molar mass of the hydrophilic portion of the molecule. M is the molar mass of the whole molecule. This metric can be especially useful in describing a well-defined molecular structure. However, the HLB does not account for how hydrophilic and lipophilic units are distributed within the molecule. For desulfonated PSS materials, a HLB value may be assignable, but the molecular structure cannot be inferred from this value.

[00149] Example 1.2. Size distribution of PDPSS polymers

[00150] The hydrodynamic diameter of the formed PDPSS polymers was measured by dynamic light scattering ("DLS") at 25 °C. The diameter reported is number weighed. As shown in FIG. 4, there is a monodisperse distribution of diameters with an average value of 7.5 ± 0.5 nm. Henceforth, the reactant PSS solution will be referred to as "Sample 0." The resulting PDPSS polymer after the desulfonation reaction shall be referred to as "Sample 1."

[00151] The hydrodynamic diameter of Sample 0 was calculated theoretically from the radius of gyration (R_g) of PSS for molecular weights of less than 100,000 daltons in a dilute concentration regime. Rg is -7.7 nm and D_H is 2.5 nm (D_H = R_g/3.08 = 2.5 nm). Based on these calculations, the average size of the polymer increased from 2.5 nm for Sample 0 (PSS) before desulfonation to 7.5 nm for Sample 1 (PDPSS) after partial desulfonation.

[00152] DLS was also used to test the stability of Sample 1 at increasing temperatures of up to 150 °C. As shown in FIG. 5, the average size of Sample 1 does not change appreciably with increasing temperatures. This indicates that Sample 1 is stable at temperatures of up to 150 °C.

[00153] Example 1.3. Effect of reaction temperature on PDPSS polymer size

[00154] The PDPSS polymer synthesis protocol outlined in Example 1.1 was repeated by varying the synthesis temperature in the microwave reactor between 80 °C and 120 °C. The hydrodynamic diameters of these samples were collected at 25 °C by DLS and compared to that of Sample 1. As summarized in FIG. 6, the produced PDPSS polymer sizes appeared to be different at each temperature. However, the PDPSS polymer size distributions continued to be monodisperse in all cases.

[00155] The increasing size of the PDPSS clusters with temperature supports the disclosure herein of a new material that has hydrophilic (sulfonated styrene units) as well as lipophobic (desulfonated styrene units) parts. As the extent of desulfonation increases, it is believed that the polymer chain curls up with the hydrophilic parts extending outward into the water-phase. Likewise, it is believed that the lipophilic sections of the polymer would curl inwards to form spherical structures that would have a larger hydrodynamic diameter than the straight chain PSS.

[00156] Example 1.4. Stability of PDPSS polymers in brine

[00157] To test the stability of PDPSS polymers in brine, Sample 1 was diluted to 0.5 wt in API brine (8 wt NaCl, 2 wt CaCl₂, and 90 wt DI H₂0). Sample 1 continued to be stable in API brine for weeks. Moreover, the average size of the PDPSS polymers in Sample 1 remained the same. As shown in FIG. 7, the hydrodynamic diameter of the PDPSS polymers in Sample 1 is also stable at temperatures up to 150 °C. Such results indicate that PDPSS polymers are stable at extreme conditions of high temperature and high salinity. [00158] Example 1.5. UV-vis spectroscopy of PDPSS polymers

[00159] Ultraviolet-visible optical absorption spectroscopy (UV-vis) of Sample 0 and Sample 1 was performed to track any changes with the sulfonate group. The results are shown in FIG. 8. The first peak around 200 nm and the second peak around 225 nm are from the aromatic pi-pi* transitions in sulfonated styrene. The increase in the intensity of peaks 2 and 3 in Sample 1 indicates desulfonation. However, the presence of these peaks in both spectra indicates that complete desulfonation did not occur. The relative intensity of peak 2 has increased in Sample 1 compared to Sample 0, indicating more aromaticity in Sample 1 as a result of desulfonation. The third peak at around 260 nm represents styrene units. When comparing the relative intensity of this peak in Sample 1 to that in Sample 0, it is evident there are more desulfonated styrene units in Sample 1. This confirms that Sample 1 contains PDPSS polymers.

[00160] Example 1.6. Nile Red test on PDPSS polymers

[00161] Nile Red (9-diethylamino-5-benzo[a]phenoxazinone) is a lipophilic dye that does not dissolve in aqueous solvents, such as DI water. When Nile Red was added to Sample 0, the dye powder stayed out of solution due to the lipophilic nature of the dye (FIG. 9A). However, the addition of the dye to Sample 1 produced a uniform, deep blue color (FIG. 9B). The color change indicates that the PDPSS polymers in Sample 1 act as a stabilizer for the dye due to the presence of both hydrophobic and hydrophilic parts.

[00162] Example 1.7. Suspension of carbon black by PDPSS polymers

[00163] Commercially available carbon black with an average cluster size of 15 nm was added to Sample 0 and Sample 1 followed by bath sonication for 10 minutes. The hydrophobic carbon black remains a distinct phase in Sample 0 (FIG. 10A). However, the carbon black forms as a stable suspension in Sample 1 (FIG. 10B). Moreover, the suspension remained stable for over 2 weeks.

[00164] Example 1.8. Oil-water interface studies of PDPSS polymers

[00165] With preliminary evidence supporting detergent-like properties of PDPSS polymers, Applicants aimed to quantify the surface activity of PDPSS at an oil-water interface. Accordingly, an API brine solution was filled in a thin capillary. Next, a drop of toluene was added as the oil phase. The capillary was inserted in a Spinning Drop Interfacial Tensiometer (Model 500) at a spinning time period of 8.09 ms/revolution. The diameter of the toluene drop was measured earlier using a digital camera that was pre -calibrated using a standard sample. The experiment was conducted at 25 °C and monitored for 2 hours to track any changes with time. The interfacial tension ("IFT") between the toluene and aqueous phase is given by Equation 2 below:

[00166] In Equation 2, γ is IFT in dyne/cm (1 dyne/cm = 1 mN/m), T₀ is the spinning time period in ms/rev, D₀ is the diameter of oil drop in mm, and AS is the specific gravity difference between the PDPSS solution and toluene. In addition, n_w and n are the refractive index of water and the PDPSS solution, respectively.

[00167] As shown by the y-coordinate value in FIG. 11, the diameter of the toluene drop was 0.2627 mm. Substituting this back into the IFT equation, an IFT value of 1.94 x 10^"2 dyne/cm (1 dyne/cm = lmN/m) was obtained. Such a value places PDPSS polymers in the range of surfactants suitable for use in enhanced oil recovery ("EOR"). Moreover, it is anticipated that optimization of the preparation chemistry will lead to lower IFT values, which are desirable in EOR.

[00168] The IFT of Sample 1 in API brine was also measured as a function of time to see how it changes. As seen in FIG. 12, the IFT value remains constant at 1.9 x 10^"2 dyne/cm for over 2 hours. This indicates that the surface activity of PDPSS may not change with time spent underground.

[00169] While it was known that the size of PDPSS will not fluctuate with temperature, it was also desired to confirm that the surface activity of the PDPSS polymers would not decrease with temperature. Accordingly, spinning drop tensiometry of Sample 1 in API brine was performed using a toluene drop at 3 different temperatures: 25 °C, 50 °C, and 75 °C. As seen in FIG. 13, the IFT value did not increase but actually lowered further. While the reservoir temperatures may well be higher than 75 °C, the trend suggests that IFT values can be even lower at higher temperatures.

[00170] The IFT values clearly indicate that PDPSS polymers are a surface active material with the potential to act as a chemical aid in oil and/or gas recovery. As a reference, the IFT of pure water and toluene is 37.1 dyne/cm, the IFT of brine (11 wt CaCl₂) and toluene is 30.5 dyne/cm, and the IFT of PSS (mol. wt. 600 kDa, 2 wt in water) and toluene is -20 dyne/cm. As noted, surfactants suitable for use in EOR may have an IFT on the order of 10^"3 dyne/cm. The test results indicate that IFT has been substantially lowered in Sample 1 (PDPSS) as compared to PSS. In addition, the IFT of PDPSS polymers is in the same range as those surfactants suitable for use in EOR processes. The aforementioned IFT values are summarized in Table 1, which provides a summary of the IFT of various samples with toluene at room temperature, as compared to Sample 1 in API brine.

Table 1 [00171] Example 1.9. Effect of PSS molecular weight on the size of the PDPSS polymers

[00172] In order to study the effects of PSS molecular weight on the size of the formed PDPSS polymers, PSS was used with a molecular weight of 1 megadalton (1000 kDa) and ran a similar experiment as done with Sample 1 for comparing the effect of PSS molecular weight. The resulting product is referred to as Sample 2 henceforth.

[00173] As shown in FIG. 14, there is a significant increase in size of PDPSS polymers with the higher molecular weight PSS. A relative viscosity comparison was also performed of these two samples using an Ostwald viscometer, indicating that there is a 5-fold increase in shear viscosity of Sample 2 as compared to Sample 1.

[00174] Example 1.10. Breakthrough of PDPSS polymers through a sand packed column

[00175] Sample 1 was diluted to Ι/Ιθ"¹ by volume in API brine and a laboratory scale column flow experiment was performed using crushed Berea sandstone and sea sand to simulate the underground reservoir conditions. First, a glass column of height 7.6 cm was filled with crushed sandstone and the column flushed with API brine at a constant flow rate of 2 mL/h for 18 hours. Thereafter, the base case material was flushed through the column at a constant flow rate of 8 mL/h. Next, samples were collected downstream of the column every 6 minutes. The concentration of the polymer was calculated from UV-vis spectroscopy while the volume of samples collected downstream was converted in terms of pore volume of the column which in turn was obtained using a tracer experiment. As shown in FIGS. 15-16, the material reached >95 breakthrough quickly, indicating that it does not interact with the column material (i.e., Sample 1).

[00176] Example 1.11. PDPSS polymer formation in the presence of co-solvents

[00177] In Example 1.1, DI H₂0 was the only solvent used during the microwave synthesis of PDPSS polymers. Though the synthetic scheme in Example 1.1 is stronger at low pH and high temperatures, it has been shown that microwave synthesis can affect the synthesis of PDPSS polymers.

[00178] In particular, the non-thermal effect of microwaves on a solvent can be quantified by its loss tangent, which indicates how well a solvent can absorb microwave energy and convert it to thermal energy. Since a fast microwave -induced heating rate is utilized, which results in the attainment of the set temperature in approximately 1 minute, the loss tangent would only indicate what fraction of the absorbed microwave energy is converted to heat.

[00179] Water has a loss tangent of 0.123. Therefore, a soluble co-solvent was selected with a higher loss tangent (i.e., formic acid, which has a loss tangent of 0.722) to aim for higher desulfonation.

[00180] As outlined in Example 1.1, a 5 wt solution of PSSNa was made using the solvents listed in Table 2. The microwave was used to quickly heat the sample to 160 °C. The sample was held at that temperature for 5 minutes and then cooled down to 55 °C.

[00181] Next, hydrodynamic diameters (D_H) of the samples were measured by the same method outlined in Example 1.2. In addition, the IFT of the samples was measured by the same method outlined in Example 1.9. The results are summarized in Table 2, which provides a summary of the properties PDPSS polymers formed in different solvents. Solvent used (+ 0.1 M HC1) pH measured D_H (in nm) IFT w/toluene (in mN/m)

100% H₂0 1 7.5 1.82x10²

97.5% H₂0, 2.5% formic acid 1.12 7.5 1.82x10²

95% H₂0, 5% formic acid 0.95 11.1 9.4x10³

92.5% H₂0, 7.5% formic acid 0.92 11.4 8.2x10³

90% H₂0, 10% formic acid 0.92 11.4 8.2x10³

Table 2

[00182] To confirm that microwave heating contributed to the properties of the formed PDPSS polymers, the same experiment with a 90% H₂0 and 10% formic acid solvent was repeated in a silicon carbide (SiC) vessel instead of a standard quartz vessel. SiC strongly absorbs the microwave radiation while still letting the heat through to the sample inside. The results are summarized in Table 3, which provides a summary of the properties PDPSS polymers formed in different vessels.

Table 3

[00183] When the secondary microwave effect was eliminated, the effect of the formic acid was also nullified. Without being bound by theory, the results indicate that there is a primary pH/temperature effect and a secondary microwave radiation effect that amplifies the primary effect. This secondary effect was not perceived at milder synthesis conditions of a pH of more than 2 and temperatures of less than 120 °C. Therefore, it is believed that such secondary effects are prevalent at more extreme pH and temperature values. In sum, the results indicate that the utilization of a co-solvent at more extreme reaction conditions (e.g., pH of less than 1 and temperatures of more than 160 °C) can result in replicable IFT values that are less than 10^"3 mN/m.

[00184] Example 1.12. Comparison of the IFTs of PDPSS polymers with other materials

[00185] In Example 1.9, the IFT was measured with Sample 1 at 5000 ppm in API brine (8 wt% NaCl, 2 wt% CaCl₂, and 90 wt% DI H₂0) with toluene as the oil phase. In this Example, the IFT value of PDPSS polymers (synthesized at pH 1 and 200 °C) in toluene was compared with different compositions at room temperature. The results are summarized in Table 4, which provides a summary of the IFT values of various compositions. System IFT (in mN/m) at 25 °C

Deionized water/Toluene 37.1

API brine/Toluene 30.5

PSS (50,000 ppm in API brine)/Toluene 16

PSSNa (5000 ppm) in API brine/toluene 16

SDBS (5000 ppm) in API brine/toluene 0.5

Enordet (5000 ppm, Commercial EOR

surfactant) in API brine/Toluene l.lxlO ²

Partially desulfonated PSS (5000 ppm in

API brine)/toluene 1.25xl0^'2

Table 4

[00186] Example 1.13. Testing the effect of different oil phases in IFT measurements

[00187] Toluene is an aromatic oil. Therefore, as a comparison to the measurements in Example 1.9, the IFT of Sample 1 was also measured against Isopar-L (a blend of Cn-Ci₃ alkanes with <2 aromatics).

[00188] FIG. 17 shows the IFT values of a specific PDPSS polymer sample synthesized at pH 1 and 160 °C in different oils. Each sample was diluted to 5000 ppm in API brine. All measurements were done at 25 °C.

[00189] This comparison was performed to determine how the PDPSS polymer behaves with a highly aromatic oil (i.e., toluene) when compared to a highly aliphatic oil (i.e., Isopar-L). With 100% Isopar- L, IFT increased to 0.75 mN/m. However, since crude oil has a much larger fraction of aromatic content, lower IFT values are expected when the PDPSS polymers are utilized in oil recovery.

[00190] In addition, an exponential fit was performed on the data to model the IFT of this specific sample (in API brine) against aliphatic content in a tested oil sample. Equation 3 was utilized for the exponential fit:

IFT = 0.0178 e" (3)

[00191] In Equation 3, x is the percentage of the aliphatic content (i.e., Isopar-L) in an oil blend. Thus, Equation 3 can be utilized to estimate the aliphatic content of an unknown oil composition through the IFT value of the sample. [00192] Example 1.14. Testing the effect of salinity in IFT measurements

[00193] Table 5 compares the IFT values of PDPSS polymers in toluene at room temperature. The PDPSS polymer was synthesized at pH 1 and 200 °C under different salinity conditions. The results are summarized in Table 5, which provides a summary of the IFT values of different PDPSS polymer samples.

Table 5

[00194] The results indicate that, once the salinity conditions are optimized for an oil type, low to ultralow IFTs (e.g., IFTs <10 mN/m) can be achieved in a reliable manner.

[00195] Example 2. Alternative Routes for the Synthesis of Partially Sulfonated Polymers

[00196] This Example demonstrates the preparation of partially sulfonated copolymers by the sequential polymerization, copolymerization, or post polymerization modification of either homopolymers or copolymers of various compositions. Examples of each route are illustrated in FIGS. 18A-C.

[00197] In the illustrations in FIG. 18, the monomers are styrenic. However, the use of other monomers can be envisioned. These embodiments allow systematic variation of polymer morphology and molecular weight, as well as monomer identity and incorporation ratios. Additionally, these embodiments allow for the control of end group chemistry. The control of end group chemistry can in turn allow for the attachment of PDPSS to surfaces, including those of 0 d, 1 d, 2 d, and 3 d materials. Some embodiments include partially sulfonated polymers prepared by combinations of the above mentioned processes, or polymers prepared to be used as starting materials in the above mentioned microwave mediated hydrothermal desulfonation processes. The synthetic routes herein pertain to the preparation of PSS-b-PS by sequential polymerization and post-polymerization modification.

[00198] Example 2.1. Preparation of a polystyrene macroinitiator (PS-MI)

[00199] Styrene (68 mmol, 7.8 mL), Cu(II)Br₂ (0.3 mmol, 68 mg), and pentamethyldiethylenetetramine (PMDETA, 0.3 mmol, 52 mg) were added to a 50 mL round bottom flask. The mixture was degassed by subsurface sparging with N₂. Thereafter, the mixture was heated to 110°C in a thermostated oil bath. Next, a degassed solution of Sn(II) 2-ethylhexanoate (1 mL, 0.15 M in PhMe, 0.151 mmol) was added via syringe to initiate polymerization. After 12 hours, the reaction mixture was opened to the atmosphere, cooled to room temperature, and diluted with tetrahydrofuran( THF). The resulting mixture was filtered through A1₂0₃ and precipitated by addition to hexanes to yield 2.3 g of polystyrene macroinitiator ("PS-MI") as a white solid. Gas phase chromatography (GPC) analysis indicated a M_n of 7890 g mof¹ and a PDI of 1.14. [00200] Example 2.2. Chain extension of PS-MI

[00201] PS-MI (0.005 mmol, 50 mg), Cu(II)Br₂ (0.1 mL, 0.02M in DMF, 0.002 mmol), PMDETA (0.1 mL, 0.02M in DMF, 0.002 mmol), 4-vinylbenzene sulfonate, and neopently ester (1.10 mmol, 280 mg) were added to a 50 mL round bottom flask. PhMe (5 mL) was added to the mixture. The mixture was then degassed by subsurface sparging with N₂. The mixture was heated to 110°C in a thermostated oil bath. Next, a degassed solution of Sn(II) 2-ethylhexanoate (0.8 mL, 0.02 M in PhMe, 0.01 mmol) was added via syringe to initiate polymerization. After 48 hours, the reaction mixture was opened to the atmosphere, cooled to room temperature, and diluted with THF. The resulting mixture was filtered through A1₂0₃ and precipitated by addition to MeOH to yield 120 mg of polystyrene-Wocfc-polystyrene sulfonate neopentyl ester (PS-&-PSSNE) as an off-white solid. GPC analysis indicated a M_n of 11400 g mol^"1 and a PDI of 1.64.

[00202] Example 2.3. Post polymerization modification of block copolymer

[00203] 15 mg of PS-6-PSSNE was added to a 6 dr. vial. The solid was then heated to 150 °C for 1 hour. Thereafter, the solid was cooled to room temperature and dissolved in DMSO-d₆ for NMR analysis. The NMR analysis showed complete removal of the ester from the sulfonate block, producing a new formulation of PDS.

[00204] The embodiments described herein are to be construed as illustrative and not as constraining the remainder of the disclosure in any way whatsoever. While the embodiments have been shown and described, many variations and modifications thereof can be made by one skilled in the art without departing from the spirit and teachings of the invention. The disclosures of all patents, patent applications and publications cited herein are hereby incorporated herein by reference, to the extent that they provide procedural or other details consistent with and supplementary to those set forth herein.

Claims

WHAT IS CLAIMED IS:

1. A method for recovering hydrocarbons from a geological structure, wherein the method comprises:

injecting a composition into the geological structure, wherein the composition comprises a partially sulfonated polymer, wherein the partially sulfonated polymer comprises a polymer chain comprising a plurality of monomeric units, wherein the monomeric units comprise sulfonated monomeric units associated with sulfonate moieties, and unsulfonated monomeric units that lack the sulfonate moieties; and

collecting the composition after flow through the geological structure, wherein the flow results in association of the hydrocarbons in the geological structure with the composition.

2. The method of claim 1 , further comprising separating the hydrocarbons from the composition.

3. The method of claim 1, wherein the injecting occurs in a first location of the geological structure, and wherein the collecting occurs in a second location of the geological structure.

4. The method of claim 1, wherein the composition further comprises surfactants.

5. The method of claim 1, wherein the composition further comprises saltwater.

6. The method of claim 1, wherein the geological structure is a hydrocarbon reservoir.

7. The method of claim 1, wherein the polymer chain of the partially sulfonated polymer is selected from the group consisting of sulfonated poly( vinyl alcohol), sulfonated polyurethane, sulfonated poly (ethylene glycol), sulfonated poly(propylene glycol), sulfonated poly(ethylene imine), sulfonated sorbitol, sulfonated polysaccharides, sulfonated polylactone, sulfonated polyacrylates, sulfonated polyacrylonitrile, sulfonated polyethylene, sulfonated polyvinyls, sulfonated poly(vinyl chloride), sulfonated

polyacrylamides, sulfonated poly(acrylic acid), sulfonated polystyrene, sulfonated high impact polystyrene, sulfonated polypropylene, sulfonated polyester, sulfonated poly(hydroxyalkyl ester), sulfonated poly (butadiene), sulfonated vinyl polymers, and combinations thereof.

8. The method of claim 1, wherein the polymer chain of the partially sulfonated polymer comprises sulfonated polystyrene.

9. The method of claim 1, wherein the sulfonated monomeric units of the partially sulfonated polymer are selected from the group consisting of sulfonated vinyl alcohols, sulfonated urethanes, sulfonated ethylene glycol, sulfonated propylene glycol, sulfonated ethylene imine, sulfonated saccharides, sulfonated lactone, sulfonated acrylates, sulfonated acrylonitrile, sulfonated ethylene, sulfonated vinyls, sulfonated vinyl chloride, sulfonated acrylamides, sulfonated acrylic acid, sulfonated styrene, sulfonated propylene, sulfonated hydroxy alkyl ester, sulfonated butadiene, and combinations thereof.

10. The method of claim 1, wherein the sulfonated monomeric units of the partially sulfonated polymer comprise sulfonated styrene.

11. The method of claim 1 , wherein the sulfonate moieties of the sulfonated monomeric units comprise the following chemical formula:

-SO₃R,

wherein R is selected from the group consisting of H, Na, K, Li, NH₄, alkyl groups, aryl groups, phenyl groups, and combinations thereof.

12. The method of claim 1, wherein the unsulfonated monomeric units of the partially sulfonated polymer are selected from the group consisting of vinyl alcohols, urethanes, ethylene glycol, propylene glycol, ethylene imine, saccharides, lactone, acrylates, acrylonitrile, ethylene, vinyls, vinyl chloride, acrylamides, acrylic acid, styrene, propylene, hydroxyalkyl ester, butadiene, and combinations thereof.

The method of claim 1 , wherein the unsulfonated monomeric units of the partially sulfonated ymer comprise styrene.

14. The method of claim 1, wherein the unsulfonated monomeric units of the partially sulfonated polymer comprise between about 5% to about 90% of the monomeric units of the polymer chain.

15. The method of claim 1, wherein the partially sulfonated polymer has an interfacial tension that ranges from about 1 x 10^~2 dyne/cm to about 10 x 10^"2 dyne/cm.

16. A partially sulfonated polymer, wherein the partially sulfonated polymer comprises:

a polymer chain comprising a plurality of monomeric units,

wherein the monomeric units comprise

sulfonated monomeric units associated with sulfonate moieties, and unsulfonated monomeric units that lack the sulfonate moieties.

17. The partially sulfonated polymer of claim 16, wherein the polymer chain is selected from the group consisting of sulfonated poly( vinyl alcohol), sulfonated polyurethane, sulfonated poly(ethylene glycol), sulfonated poly(propylene glycol), sulfonated poly(ethylene imine), sulfonated sorbitol, sulfonated polysaccharides, sulflonated polylactone, sulfonated polyacrylates, sulfonated poly aery lonitrile, sulfonated polyethylene, sulfonated polyvinyls, sulfonated poly(vinyl chloride), sulfonated

polyacrylamides, sulfonated poly(acrylic acid), sulfonated polystyrene, sulfonated high impact polystyrene, sulfonated polypropylene, sulfonated polyester, sulfonated poly(hydroxyalkyl ester), sulfonated poly (butadiene), sulfonated vinyl polymers, and combinations thereof.

18. The partially sulfonated polymer of claim 16, wherein the polymer chain comprises sulfonated polystyrene.

19. The partially sulfonated polymer of claim 16, wherein the sulfonated monomeric units are selected from the group consisting of sulfonated vinyl alcohols, sulfonated urethanes, sulfonated ethylene glycol, sulfonated propylene glycol, sulfonated ethylene imine, sulfonated saccharides, sulfonated lactone, sulfonated acrylates, sulfonated acrylonitrile, sulfonated ethylene, sulfonated vinyls, sulfonated vinyl chloride, sulfonated acrylamides, sulfonated acrylic acid, sulfonated styrene, sulfonated propylene, sulfonated hydroxyalkyl ester, sulfonated butadiene, and combinations thereof.

The partially sulfonated polymer of claim 16, wherein the sulfonated monomeric units comprise bnated styrene.

21. The partially sulfonated polymer of claim 16, wherein the sulfonated monomeric units are derived from the unsulfonated monomeric units.

22. The partially sulfonated polymer of claiml6, wherein the sulfonate moieties comprise the following chemical formula:

wherein R is selected from the group consisting of H, Na, K, Li, NH₄, alkyl groups, aryl groups, phenyl groups, and combinations thereof.